Integrates https://github.com/cesanta/mongoose/pull/884
Closes https://github.com/cesanta/mongoose/issues/883

CL: Mongoose Web Server: Don't use user_data in mqtt server

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CL: Mongoose Web Server: Fix mg_parse_multipart in case of malformed request

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CL: none

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CL: Mongoose Web Server: Fix publish-subscribe example

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CL: Mongoose Web Server: Fix socket leak when there are too many open file descriptors

Fixes https://github.com/cesanta/mongoose/issues/870

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Fixes https://github.com/cesanta/mjs/issues/82
Integrates https://github.com/cesanta/mjs/pull/85

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CL: Fix OOB access in mg_match_prefix_n().
    Made mg_match_prefix_n() return non-negative result.

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CL: Fix TCP RX path regression in SSL mode

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CL: - Mongoose Web Server: close undrained and stuck http connections

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h/t @kzyapkov

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AWS MQTT connection works

Also fixes https://github.com/mongoose-os-libs/ethernet/issues/1 (because why not).

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Standardize common packages in build images, to make better use of Docker image cache.

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PUBLISHED_FROM=e5b829d93ecf946e5bdbbf33132be7068ffe0dd2

PUBLISHED_FROM=1bfc6e332f56b68eb6155bb729a97a0d8d5a316c

To avoid name clashes.

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2.0 redefined LWIP_VERSION in a way that is no longer compatible with use by preprocessor (boo).
also, tcp_pcb.acked is gone, but we only use it for debug, so it doesn't matter.

PUBLISHED_FROM=776f90a08bd5024fa8a61dae257af6c60ec6710d

ECDHE is way too slow on ESP8266 w/o cryptochip, this sometimes results in WiFi STA deauths.
Disable DHE completely because it's just hopelessly slow.

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Make sure topic is properly NUL-terminated.
Ignore SUBSCRIBE requests with no topic expressions.

PUBLISHED_FROM=a00f39dda44fe63299e971a91a98f8ee57dd2a64

NULL out cgi_nc->user_data so it doesn't touch nc anymore.

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Must set SSL parameters before invoking sl_Listen

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ev_timer_time may remain the same for legit reason, so to prevent looping, instead, reset it before invoking the handler.
To let user know what the initial setting was, pass it as the argument instead of current time (which is kind of pointless).

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